UNIVERSITY  OF  CALIFORNIA  agricultural  experiment  station 

COLLEGE  OF  AGRICULTURE  THOMAS   FORSYTH   HUNT,  DIRECTOR 

BERKELEY,  CALIFORNIA 

CIRCULAR  No.  84 

Mushrooms  and  Toadstools. 

By  W.  A.   Setchell. 

(January,  1913.) 

What  is  a  toadstool?  The  answer  of  the  botanist  is  that  a  toad- 
stool is  any  one  of  the  fleshy  umbrella-shaped  fungi  which  commonly 
are  called  by  that  name  or  by  the  name  of  ■ '  mushroom. '  •  The  popular 
desire,  however,  seems  to  be  to  restrict  the  name  "toadstool"  to  the 
poisonous  species  and  that  of  "mushroom"  to  the  edible  species.  This 
is,  however,  very  unsatisfactory,  since  one  cannot  tell,  except  by  trial, 
whether  a  particular  toadstool  is  poisonous  or  not.  Edible,  innocent, 
and  poisonous  toadstools.  A  few  toadstools  are  extremely  poisonous, 
a  considerable  number  are  probably  slightly  poisonous,  most  toadstools 
are  innocent,  i.  e.,  not  poisonous,  and  some  of  the  innocent  species  are 
edible.  Edibility  implies  that  only  those  innocent  species  which  are  of 
fair  size,  sufficiently  delicate  texture,  and  of  agreeable  flavor  are  to 
be  included  in  the  list. 

How  may  one  tell  an  innocent  from  a  poisonous  toadstool?  The 
popular  mind  always  seeks  some  test  which  may  be  applied.  Such  a 
test  should,  of  course,  be  decisive  and  of  uniform  result.  Many 
reputed  tests  pass  current  and  are  implicitly  believed  in  by  some.  So 
far  as  is  known  there  is  no  single  test,  short  possibly  of  chemical 
analysis,  which  will  give  results  of  any  value  whatsoever!  It  may  be 
well  to  mention  some  alleged  tests  in  order  to  emphasize  their  unreli- 
ability and  their  danger. 

UNRELIABLE  TESTS. 

1.  The  so-called  "Silver  Test"  is  one  most  prevalent.  It  is  believed 
that  a  silver  spoon  or  coin  placed  with  the  toadstools  while  cooking 
will  demonstrate  by  blackening  or  failure  to  blacken  whether  the 
toadstools  are  safe  to  eat  or  not.  It  need  only  be  said  in  criticism  that 
there  are  both  poisonous  and  innocent  species  which  act  alike  on  silver. 
This  test  is  therefore  of  no  value. 

2.  Some  say  that  if  the  outer  (upper)  skin  of  the  top  of  the  toad- 
stool peels  off  readily,  that  such  a  species  is  edible.  It  may  be  said 
that  certain  edible  species  will  "peel"  and  other  edible  species  will 
not  "peel."  Some  poisonous  species  also  will  "peel."  So  there  is 
no  reliance  to  be  placed  on  this  "test." 

3.  It  is  alleged  that  edible  toadstools  while  raw  have  an  agreeable 
flavor  when  tasted  (in  minute  quantities  as  a  rule)  while  poisonous 
species  are  bitter  or  peppery,  or  even  disagreeable  in  flavor.  Some 
disagreeably  flavored  toadstools  are  innocent  and  even  of  agreeable 
flavor  when  cooked,  while  some  others  are  looked  upon  with  suspicion 
and  reputed  poisonous.  The  most  poisonous  toadstools,  however, 
are,  at  least,  not  at  all  disagreeable  as  regards  the  flavor  of  the  raw 
flesh.  Consequently,  this  test  offers  no  certain  way  to  distinguish 
poisonous  from  innocent  or  edible  toadstools. 


—  2  — 

4.  When  one  breaks  open  a  toadstool  or  bruises  it,  it  ma}'  change 
color  or  it  may  not.  Sometimes  the  change  is  to  light  or  to  dark  blue, 
sometimes  to  a  reddish  or  brownish  tint  of  darker  or  lighter  hue. 
This  may  or  may  not  be  significant,  but  it  is  no  reliable  test  of  a  general 
character.  In  general,  any  decided  change  of  color  should  arouse  sus- 
picion, but  the  lack  of  it  gives  no  indication  whatsoever  as  to  the  nature 
of  the  toadstool. 

5.  Some  toadstools  when  broken  open  show  a  milky  juice.  This  is 
usually  white  but  may  be  red,  orange,  or  blue.  Some  such  toadstools  are 
regarded  as  poisonous,  others  are  well  known  to  be  innocent,  and  some 
are  delicious  eating.  On  the  other  hand  the  lack  of  a  milky  juice  is 
no  evidence  of  either  non-poisoncus  or  of  poisonous  character. 

6.  Many,  if  not  all,  toadstools  are  liable  to  be  infested  by  insects, 
whose  larvae  are  often  so  abundant  within  the  plant  (often  without 
any  external  evidence  of  it)  that  the  toadstools  are  fairly  honeycombed 
by  their  ravages.  Some  take  this  as  an  indication  of  a  non-poisonous 
nature  on  the  part  of  the  toadstool.  Experience  has  shown,  however, 
that  this  is  not  so,  but  that  the  insects  attack  both  poisonous  and  non- 
poisonous  species. 

MORE  CERTAIN  METHODS. 

There  are,  then,  no  tests  to  be  applied  with  any  certainty  and  the 
question  still  before  us,  is:  How  may  one  tell  the  poisonous  from  the 
innocent  species  ?     There  are  two  methods : 

I.  By  eating  them!  This  is,  however,  a  tedious  process  and  one 
attended  with  more  or  less  danger.  It  is  not  to  be  recommended,  espec- 
ially to  the  beginner.  If  tried,  the  following  process  is  usually  recom- 
mended. A  very  small  bit  of  the  raw  toadstool  is  chewed  but  none  of 
the  juice  swallowed.  If  after  24  hours  no  disagreeable  result  is 
experienced,  a  similar  bit  is  chewed  and  some  of  the  juice  swallowed. 
If  after  a  similar  interval,  no  disagreeable  symptoms  result,  a  small 
piece  may  be  chewed  and  swallowed.  If  nothing  suspicious  occurs  after 
24  or  36  hours,  a  fair  quantity  may  be  tested  by  cooking  and  eating.  It 
is  proper  to  warn  the  novice  that  this  may  be  done  safely  only  after 
learning  to  distinguish  the  most  poisonous  species  (especially  the 
species  of  Amanita  mentioned  later  on),  since  of  some  of  these  it  needs 
only  a  very  small  piece  to  produce  serious  poisonous  effects. 

II.  By  learning  of  the  experience  of  others.  There  has  been 
accumulated  a  certain  amount  of  knowledge  concerning  the  innocent 
or  poisonous  character  of  toadstools.  While  this  body  of  knowledge 
it  not  complete  and  while  there  are  certain  parts  of  it  about  which 
there  is  lack  of  agreement,  a  considerable  number  of  toadstools  are 
well  known  t<>  be  either  poisonous  or  edible.  How  then  is  one  to  avail 
himself  of  this  knowledge  .'  By  studying  the  toadstools  and  the  various 
books  written  on  the  subject.  Much  that  is  reliable  and  satisfactory 
may  be  learned  in  this  way.  One  must  learn  to  know  the  various 
kinds  of  toadstools  as  one  learns  to  know  the  ordinary  plants  of  hill 
and  forest   and  garden. 


—  3  — 

What  are  the  distinguishing  marks  of  difference  among  toadstools? 

I.  In  general,  each  toadstool  possesses  an  upper  flattened  horizontal 
structure  which  is  usually  called  the  "cap,"  or  botanically,  the 
"pileus,"  and  a  stalk,  botanically  called  the  ''stipe."  In  some  cases, 
the  stalk  or  stipe  fits  into  a  swollen  cup-like  structure  at  the  base 
which  is  called  the  "volva."  The  presence  or  absence  of  a  volva  is  a 
matter  of  considerable  importance;  consequently  in  studying  toad- 
stools one  should  be  careful  to  obtain  the  very  base.  Many  toadstools 
have  a  sort  of  ring  or  collar  encircling  the  stipe  somewhere  between 
the  base  and  the  pileus. 

II.  Structures  of  very  great  importance  are  those  found  on  the  under 
side  of  the  cap  or  pileus.  This  portion  of  the  pileus  is  called  the 
"hymenium."  By  the  difference  in  the  structure  of  the  hymenium, 
toadstools  may  be  divided  into  four  classes,  as  follows : 

1.  Hymenium  smooth.  There  are  not  many  toadstools  in  this  group  and  few 
of  them  of  a  texture  sufficiently  soft  to  allow  of  eating.  There  are  no  poisonous 
species  known  in  this  group. 

2.  Hymenium  spiny.  These  are  called  "Hedgehog  Toadstools  or  Mushrooms." 
The  species  possible  of  being  eaten  are  few  and  none  of  them,  so  far  as  is  known, 
is  poisonous. 

3.  Hymenium  porose.  The  hymenium  in  the  toadstools  of  this  group  is  made  up 
of  closely  crowded  tubes,  perpendicular  to  the  horizontal  diameter  of  the  pileus, 
as  may  be  seen  by  breaking  the  pileus  open.  It  is  the  mouths  or  openings  of  these 
tubes  which  give  the  surface  of  the  hymenium  its  porous  or  spongy  appearance. 
There  are  many  species  in  this  group  ;  some  are  innocent  and  some  are  poisonous. 
They  are  all  to  be  avoided  by  the  beginner  until  he  has  learned  to  distinguish 
them  from  the  descriptions  or  pictures  in  the  books  or  has  had  the  distinguishing 
characters  pointed  out  by  one  who  is  acquainted  with  them. 

4.  Hymenium  made  up  of  "gills."  "Gills"  are  flattened,  knife-blade-like  struc- 
tures radiating  out  from  the  center  of  the  lower  side  of  the  pileus  or  cap  to  the 
circumference.  Some  extend  from  the  place  where  the  stipe  joins  the  under  side  of 
the  pileus  to  the  circumference,  while  shorter  ones  extend  from  some  point  farther 
out  to  the  circumference.  By  far  the  larger  number  of  toadstools  are  of  this 
fourth  class  and  are  called  "Agarics."  The  Agarics  are  divided  into  5  subclasses 
by  the  color  of  their  spores.  In  order  to  determine  the  color  of  their  spores  it  is 
necessary  to  remove  the  pileus  (which  should  be  fairly  young  and  fresh)  from 
the  stipe  and  place  it,  hymenium-side  down,  on  a  piece  of  paper,  preferably  of  a 
light  gray,  brown,  or  blue.  It  is  also  advisable  to  cover  the  pileus  with  a  tumbler 
or  dish  so  as  to  prevent  too  rapid  drying.  In  from  one  hour  to  several,  according 
to  the  species,  the  spores,  which  are  the  minute  bodies  from  wmich  the  toadstools 
grow  again,  will  be  expelled  from  the  surface  of  the  gills  onto  the  paper  in  such 
quantity   as   to   indicate   the  color.     The   colors   are   as   follows : 

(a)  White.  The  majority  of  Agarics  are  in  this  subclass.  Those  of  this  sub- 
class having  a  cup  or  swollen  bulb  at  the  base  accompanied  by  a  ring  half  to  three- 
quarters  up  the  stipe  are  to  be  avoided,  for  these  belong  to  the  species  of  Amanita 
and  some  of  them  are  among  Hie  most  poisonous  of  toadstools.  Those  of  this 
subclass  having  the  solid  portion  of  the  pileus  thin  in  proportion  to  the  gills  and  in 
which  the  gills  are  nearly  all  of  equal  length  are  to  be  avoided,  especially  if  the 
top  of  the  pileus  is  bright  colored.  Avoid  also  all  of  this  subclass  having  a  milky 
juice,  unless  the  juice  is  reddish.  Other  white-spored  Agarics  may  be  eaten,  at 
least   cautiously   at   first. 

(b)  Black.  Black-spored  Agarics  are  all  innocent  and  especially  those  in  which 
the  gills,  when  old,  change  into  inky  fluid.  They  are  to  be  eaten,  however,  before  the 
gills    turn    black. 

(c)  Ochre.  In  these  the  spores  are  yellowish  or  rusty  brown.  None  of  the 
species   is  reputed  poisonous. 

(d)  Brown.  The  spores  are  dark  brown  or  purplish  brown.  The  common 
mushroom,  with  gills  which  are  pink  changing  to  purplish  black,  and  with  a  distinct 
ring  on  the  stipe,  belongs  here  and  is  edible  as  are  most  of  the  species.  Some, 
however,  are  under  suspicion. 

(e)  Rose  or  Red.  Some  of  the  pink-spored  forms  are  under  suspicion,  but  those 
with  deep  red  spores  and  a  volva,  but  without  a  ring,  are  edible. 


WHAT  TO  AVOID. 

1.  All  toadstools  in  the  young  or  "button"  stage.  At  this  time  it 
is  impossible  to  determine,  except  after  long  experience,  some  poisonous 
species  from  some  edible  species. 

2.  Avoid  all  those  with  pores  on  the  under  side  of  the  cap  until  suffi- 
cient acquaintance  teaches  the  difference  between  edible  and  poisonous 
varieties. 

3.  Avoid  all  species  with  gills,  white  spores,  a  ring,  and  a  volva  or 
bulb-like  base.     The  most  poisonous  species  are  in  this  group. 

4.  Avoid  those  having  a  milky  juice  unless  the  milk  is  red. 

5.  Avoid  those  having  the  cap  thin  in  comparison  with  the  gills, 
especially  if  they  are  bright  colored. 

6.  Avoid  all  toadstools  which  are  not  strictly  fresh  since  decay 
sometimes  greatly  increases  poisonous  substances.  By  following  these 
rules  implicitly  one  may  avoid  the  most  poisonous  kinds,  but  the  novice 
should  experiment  with  the  greatest  caution. 

Nature  of  Toadstool  Poisons.  Atkinson's  account  or  that  of  Ches- 
nut  recommended  in  the  list  of  books  should  be  consulted  for  definite 
information. 

Nutritive  Value  of  Toadstools.  In  general,  it  may  be  said  that 
even  the  most  nutritious  toadstools  are  of  little  nutritive  value  but 
are  valuable  as  food  accessories  or  condiments,  not,  in  any  wise,  as 
substitutes  for  the  meat  or  vegetable  ordinarily  consumed. 

Cultivation  of  Toadstools.  The  details  are  to  be  learned  from 
special  books  and  pamphlets.  The  accounts  in  the  books  by  Atkinson, 
Duggar,  and  Hard  in  the  list  given  below  are  all  excellent. 

Books.  In  general,  those  interested  should  consult  the  various  books 
and  pamphlets  on  the  subject,  which  will  lead  to  the  knowledge  of 
other  sources  of  information.  Some  to  be  found  (or  which  ought  to 
be  found)  in  many  Public  Libraries  are  the  following: 

*  Atkinson,  George  F.     Mushrooms  Edible,  Poisonous,  etc.      (Ithaca,  N.  Y.     Andrus 

&   Church,    1901). 
Chesnut,    V.    K.     Thirty   Poisonous   Plants   of   the   United    States    (U.    S.   Dept.   of 

Agriculture,    Farmers'    Bulletin,    No.    86.     Washington,    1898). 
Clements,    Frederic    E.     Minnesota    Mushrooms     (being    IV    of    "Minnesota    Plant 

Studies,"    published    by    the    University    of    Minnesota,    Minneapolis,    Minn., 

1910). 
Duggar,    B.    M.     The    Principles    of    Mushroom    Growing    and    Mushroom    Spawn 

Making.      (U.    S.    Dept.    Agriculture,    Bureau    of    Plant    Industry,    Bulletin 

No    85,   Washington,  1905.) 
*Farlow,    W.   G.     Some   Edible   and   Poisonous   Fungi.      (U.    S.   Dept.   Agriculture, 

Division  of  Vegetable  Physiology  and  Pathology,  Bulletin  No.  15,  Washington, 

1898.) 
Gibson,   W.   Hamilton.     Our  Edible  Toadstools  and   Mushrooms   and   How   to   Dis- 
tinguish Them    (New  York,  Harper  &  Brothers,  1895). 
♦Hard,  M.  E.     The  Mushroom  Edible  and  Otherwise,  its  Habitat  and  its  Time  of 

Growth.      (Columbus,   Ohio,   The  Ohio   Library  Co.,   1908.) 
Mcllvaine,    Charles.     One    Thousand    American    Fungi.      (Indianapolis,    Ind.,    The 

Bowen-Merrill  Company,  1900.) 

W.  A.  SETCHELL,  Botanist. 

♦These  are  especially  recommended  for  first  reading. 


